Two Thinks in Finland

[Zuikkis]

Some horrible images.. 



Pack opened.. It really looks like someone sprayed the internals with a garden hose. I can't believe how wet it can be. And the pack was fully disassembled and the holes in the battery box fixed less than a year ago. I believe this all must be just condensation.



Even some mold in many places ..







And it's just a few months ago when car was driving fine, although with the occasional insulation errors.. There must have been water there. Lesson learned: open the box immediately when you get the first insulation error.

[Zuikkis]

I measured all the battery modules for insulation resistance now that I have a meter. All other modules measured >550Mohm, which is maximum for the meter. But one module measured under 10M. This is perhaps the source of the insulation errors last winter.



I removed the battery and it looked "rusty" on the outside, so there definitely has been water. And once the cells were out, there actually was liquid water inside the box, so that was causing the <10M reading..



I measured module voltages, all others were at 48V (almost full) but two modules only had 44V. I plugged my "combiner board" in because it has convenient test points for individual cell voltages, so I could measure them with multimeter.



Sure enough, both 44V modules had one cell drained to 0V. However all others were fine. So only two cells lost in the entire pack. I do still have spares from my other pack, so this is not an issue.

But then the RLECs! Argh! Here's my test setup, one battery module and a Raspberry with CAN hat..



Raspberry has wifi connection so this is nice portable setup, just need external +12V that powers both Raspberry and the RLEC.

It shows this kind of output:

Balance target 4100 mV, balanced cells: 0
Module 08    Reported: 48.23 V   Calculated: 40.61 V     25 C    Status 0x80
  T:    23    23    23    23     22    23    23    23     23    23    22    22  (  22-  23)
  V:   612  4030  4021  4030   4026  4023  4018    56   3672  4038  4045  4038  (4045-  56 = 3989 mV)
24.07 11:54: Cell (56-4045)=3989 mV,  Temp (22-23),  Pack 40.61 V,  Status 0x80

Here we can see that all temperatures read fine, but some cell voltages are faulty..

Turns out that only four boards were still working. And then I have two boards from my other pack. That's not very good, only 6/32 working..

Here's the pile of broken ones:

[worry]

Ouch, that's bad. You definitely have a rather big leak somewhere.
Again, your experience here is a proof that we need to act quickly when water in the battery is suspected.

Myles still has RLEC's for sale, but I see your interest in developing new solutions. I don't have the necessary knowledge myself, but follow with interest.